Think about the chemical structure of carrageenan and agar - what do they have in common?
What are the differences between kappa, iota and lambda carrageenan? Why?
My answer:
1. Agar is extracted from seaweed and is gelling agent. It is a polymer of agarobiose, A disaccharide composed of D-galactose and 3,6-anhydro-L-galactose. Carrageenan is a generic term for several polysaccharides also extracted from seaweed. Carrageenan compounds differ from agar in that they have sulfate groups in place of some hydroxyl groups. It is also used for thickening, suspending, and gelling food products.
2. Each repeating unit of kappa carrageenan contains 25% of sulphate content, iota contains 32% of sulphate content whereas lambda contains 35% of sulphate content. Kappa and iota have the ability to form thermoreversible gels upon cooling of hot aqueous solutions containing various cations whereas lambda carageenan does not form a gel. The structure
of kappa and iota carrageenan allows segments of the two molecules to form so called doubles helices which bind the chain molecules in the three dimensional network, a gel whereas lambda carrageenan gas a structure that does not allow such double helix formation.
Gelatin
Download the articles on gelatin from the portal and discuss the following questions.
1. In recent years a lot of efforts have been initiated to find new alternatives for gelatin? Why?
Because gelatin play an important role in the food industry. It gives high quality gels in dilute solution
with a clean "melt in mouth" texture. At higher concentrations, it gives elastic gumliketextures which slowly dissolve in themouth.It is an effective emulsifying & foaming agentAs a polyelectrolyte, it is able to flocculatesuspended particles.
2. Gelatin is always considered a special/unique ingredient that find many applications in food and non-food industry. Why?
Because gelatin play an very important role in the food industry. The typical functional properties of gelatin are below :
Gel formation
Water binding
Texturising
Thickening
Emulsion formation and stabilization
Foam formation and stabilization
Film formation
Adhesion / cohesion
Protective colloidal function
3. Do you think fish gelatin can be used to replace mammalian gelatin (porcine and bovine)?
No, i think fish gelatin cannot be used to replace mammalian gelatin. Although all gelatins are composed of the same 20 amino acids, it is important to note that the uniqueness of fish gelatin lies in its amino acid content. Fish gelatin has lower amounts of proline and hydroxyproline, which are important during the hydrogen bonding of gelatin in water solutions. This results in a reduction of the gelling temperature. For example, gelatin from cod skins gels at 10C, whereas that from animal-based sources gels above room temperature.
What do carrageenan and agar have in common?
Think about the chemical structure of carrageenan and agar - what do they have in common?
What are the differences between kappa, iota and lambda carrageenan? Why?
My answer:
1. Agar is extracted from seaweed and is gelling agent. It is a polymer of agarobiose, A disaccharide composed of D-galactose and 3,6-anhydro-L-galactose. Carrageenan is a generic term for several polysaccharides also extracted from seaweed. Carrageenan compounds differ from agar in that they have sulfate groups in place of some hydroxyl groups. It is also used for thickening, suspending, and gelling food products.
2. Each repeating unit of kappa carrageenan contains 25% of sulphate content, iota contains 32% of sulphate content whereas lambda contains 35% of sulphate content. Kappa and iota have the ability to form thermoreversible gels upon cooling of hot aqueous solutions containing various cations whereas lambda carageenan does not form a gel. The structure
of kappa and iota carrageenan allows segments of the two molecules to form so called doubles helices which bind the chain molecules in the three dimensional network, a gel whereas lambda carrageenan gas a structure that does not allow such double helix formation.
Gelatin
Download the articles on gelatin from the portal and discuss the following questions.
1. In recent years a lot of efforts have been initiated to find new alternatives for gelatin? Why?
Because gelatin play an important role in the food industry. It gives high quality gels in dilute solution
with a clean "melt in mouth" texture. At higher concentrations, it gives elastic gumliketextures which slowly dissolve in themouth.It is an effective emulsifying & foaming agentAs a polyelectrolyte, it is able to flocculatesuspended particles.
2. Gelatin is always considered a special/unique ingredient that find many applications in food and non-food industry. Why?
Because gelatin play an very important role in the food industry. The typical functional properties of gelatin are below :
Gel formation
Water binding
Texturising
Thickening
Emulsion formation and stabilization
Foam formation and stabilization
Film formation
Adhesion / cohesion
Protective colloidal function
3. Do you think fish gelatin can be used to replace mammalian gelatin (porcine and bovine)?
No, i think fish gelatin cannot be used to replace mammalian gelatin. Although all gelatins are composed of the same 20 amino acids, it is important to note that the uniqueness of fish gelatin lies in its amino acid content. Fish gelatin has lower amounts of proline and hydroxyproline, which are important during the hydrogen bonding of gelatin in water solutions. This results in a reduction of the gelling temperature. For example, gelatin from cod skins gels at 10C, whereas that from animal-based sources gels above room temperature.